Continuity mistake: When Nora is driving down the road with Fromeyer at her window, he sticks his hands on the glass. Nora raises the window "catching his fingers". When looking through the windshield, you can see that the window is 3/4 of the way up, but when it cuts to the outside, it is just under the edge.
Continuity mistake: When the carolers are outside singing, Luther and Nora are inside hiding. When they cut to Nora, you can see out of the window- there's nothing there. When she leans back up from getting her yarn, the head caroler is there with some others behind her. In the next shot, they are back in place in the choir. Even if they were right outside the window in the first place, there is no way they could reposition themselves that fast.
Continuity mistake: When the scouts are trying to sell a Christmas tree to Luther and Nora, there is a wreath on the front door. They can't make the sale and go to their truck parked across the street. They tell some neighbors that the Kranks would not buy a tree. As they all look across the street at the house, the wreath has vanished. When Luther leaves for work the next morning, the wreath has returned.